Xdynamometer t type electrical



April 15, 1947. L WEAVER 2,419,100

DYNAIIOMETER TYPE ELECTRICAL msnmme ms'muisn'r Filed lay 25, 1945' Ihvehbor Virgil L. Weavr,

His Abbor'n eg.

@atented Apr. 15, 1947 'DYNAMOMETER TYPE ELECTRICAL MEASURING INSTRUMENT Virgil L. Weaver, Greenwood, Mass, .assignor to General Electric Com New York pany, a corporation of Application May 25, 1945, Serial No. 595,720

. 4 Claims. (01. 171--95) My invention relates to certain structural improvements in electrical measuring instruments with respect to assembly and disassembly, and one object is to provide an instrument of the dynamometer type having a moving elementwith one or more moving coils rotatable about one side and threaded by a fixed magnet core, wherein the entire moving element and its jeweled mounting, leadin spirals, pointer, etc., are removable-from the core structure as a unit without disassembly of either core. structure or mov-- ing element assembly. Another object of the invention is to accomplish such disassembly operation from the front of the instrument after removing the front cover and scale plate without removing the remainder of the instrument from its casing or disturbing the electrical connections at the back of the instrument. The entire instrument'may be removed from its casing from the front by removing the front cover and three holding screws at the back end of the casing.

The instrument is particularly suited for switchboard mounting, and the complete instrument and its manner of mounting on a switchboard are indicated in Fig. 1. Fig. 2 shows a perspective view of the major instrument parts I the manner of removing the armature assembly from the core assembly, and Fig. l-shows a terminal block detail on the armature assembly.

The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention, reference is made to the drawing in the following description. The instrument as designed for switchboard mounting is contained within a cylindrical case I,having a front cover 2 with a viewing window 3 therein. The rear of the casing is closed by the insulating base plate 4 on which the instrument is mounted when the instrument is assembled in the casing as shown in Fig. 1. The base 4 is stepped as shown in Fig. 2 such that its larger part, of a diameter to fit snugly inside the casing, abuts against the inside of a turned-in rim part 5 at the rear of the casing indicated in dotted lines in Fig. 2. A smaller part 6 of the base plate conforms to the shape of the rear opening in case I and protrudes through the'rear opening in the casing and supportsvarious electrical terminal bolts 1 by means of which the instrument is connected into measuring relation with electrical circuits from the back of the switchboard.

2 The instrument is firmly secured at its base plate 4 within and to the casing by three screws,.

one of which is shown at 15, which pass through ears IS. in the rear rim 5 from the rear and screw into the base plate part 4. When the screws l5 are tightened, the base. plate part 4 v is drawn tightly against the inside of rear rim section 5 of the casing, completely closing the rear of the casing and positioning the instrument centrally within the casing. The front of the casing has anintegral, substantially square outline face plate 8 extending outwardly from the cylindrical part, and the four corners of this plate have rearwardly extending bolts 9 fastened therein. The casing may thus be inserted from the front into a circular switchboard opening of a size slightly larger than the cylindrical part I of the casing until the plate 8 rests against the front of the switchboard about the opening. The switchboard will have holes Ill drilled therein for the bolts 9 so that the casing may be bolted in place as represented in Fig. l, where H represents a section of the switchboard on which the instrument is mounted.

The front cover 2 has a square shape conforming to the shape of front casing plate 8 and a turned-over rim section [2 which closely fits over the plate 8 and rests against the front of the switchboard. The front cover is'held in place by four screws l3 which enter threaded openings in studs l4 made integral with front cover plate 8. The studs l4 preferably extend forward from the heads of bolts 9 which pass through holes in plate 8 with the enlarged bolt heads welded to the front of-the plate. A gasket may be used within the cover to seal the front opening against dust.

The instrument shown may be a polyphase alternating current wattmeter having two torque producing elements acting on the same shaft H. The stationary magnetic core parts of the two elements are represented at l8 and I9. The laminations of these core parts are secured to base 4 by rods 20 which are made in sections and threaded together, and serve also as spacers between the base and core parts and between the core parts and a laminated magnetic shielding member 2| located between the two torque elements. The core parts l8 and is are similar and are made up of one-piece laminations as best shown in Fig. 3 and have an inner core part 22 extending from the outer part by a tongue 22' about which the current coil 23 is wound. The tongue 22' and inner core part 22 are generally in the shape of a hook with the radial opening through holes 82 in plate 30 and enter threaded from the shaft 3. distance torotate freely in the hair gaps 24 of their respective'cores i9 and -l8.

1 The armature coils-fl and 26' are positioned along shaft I] and are of such location and length as to freely encircle the hook-shaped core parts 22- of their respective cores when the armature .150

'assemblyisinpiace. a I -The armature assembly. maybeinserted into I place as represented in Fig. 3 and. removed as represented in-Fig. 2 only when the coils 28 and 2B are rotated into alignment with the radial .65

in prolongation with one side of the tongue.

25 in the hook of the front andrear core ele,--

ments i9 and I8 are in alignment. The lamina of shield 2i are of the same size and shape as those of the core parts and have the openings 25 in their hook parts and the gap 24 in alignment with the corresponding openings and gaps in the cores i8 and i9. While not shown in Fig. 2, the rear stationary core part i8 will have an energizing coil 23 such as is shown in Fig. 3. These coils are connected to certain of the rear terminal studs through insulated conductors some'ofwhich are shown at 21' in Fig. 2. Also mounted on the inside of the base are such resistances 28 or other circuit elements 29 as are needed in the circuits of the particular instrument employed.

The moving element assembly is completely supported from a die-cast frame part 30 which is-secured on the forward end of the stationary core assembly by three screws 3i which pass opening 38 in the ends of posts 20. The contacting surfaces between plate 30 and posts 20 are stepped and fitted as indicated about the open- ]ings 33 to obtain exact alignmenti Integral with plate 30 is an arm"34 Ofl'SllOh shape and position on plates!) (see Fig.1 3) as to pass freely into the aligned openings 35 located between the outer and inner stationary core parts wand I9 and shield 2|. The arm, extendsg toward the rear a sufilcient distance to reach; beyondthesback core 18, and the haclrendof extension 34 is provided'withan arm 36 which is of such size. 'shape,"ancl lccation as tc'psss "freely through the aligned openings "25 in the hook parts ofthestationary' core structure when the moving element .assemblyiis inserted into, place. This arm supports the rear jewel for the shaft ll of the moving coil armature system mature into place and removing it without injury is not difiicult, but reasonable care should be used to see that the armature is in line with o 25, that the parts are inserted or withdrawn axi- 5 ally and with the proper alignment of parts.

When in place,.the inserting and tightening of screws 3i provides the desired exact alignment and positioning of the moving coils in the stationary held for accurate measurement operation. The lead-in spirals for the armature coils are at the-front end of the assembly and need no wecial comment. The mica protective insulating dish for the uppermostspiral maybe seen at in Fig. 2. The outer or stationary ends of the spirals are supported and electrically connected to leads 4| fixed in insulating terminal blocks 42 supportedon the upper surface of plate 30 on either side of Jewel supporting arm 39 as shown in Fig. 4. The lead-in spirals are not depended upon for the zero restoring torque. A spiral spring t3 which may be adjusted by means or a zero adjustment device 44 through the front cover supplies the zero adjustment torque. The shaft ll also carried the pointer 45 and an aluminum vane which rotates in the gap 46 of damping magnets cured to plates 48 by screws which enter holes 56.

*Th armature terminals 4|, Fig. 4, are'comnected to certainpf' the studs 1 proiectingfrom the rear end of the instrument through wires 53,

Fig.2. and in order toreniove the armature as semhlyv from. the stationary core structure as -'"s'hown in 1='ig."2. I prefer-to disconnect the wires 53 at or near the terminal blocks, I find this maybe done conveniently from the front .of the instrument-after removing the front cover and iscale plate by the momentary use of a soldering "iron forexample. 1; The-scale'plate maybe reat the axial center of core parts 22. The upper 45 [or forward Jewel screwiflforthenioving cell system issupported' in. an "overhang 39 supportedin such jewels on such axis. The two adjacent shaft H with the opposite sides spaced in threading relation with their core parts and may be freely rotated to occupy various positions around the gap 24. A mid-deflection position is 'armeture 118 26 and 26' have one coil sidelclosely fifdesiredthe cover 2 may moved without injury to or removaloi' the pointer bytlpping the scaleplate slightly and sliding it off sideways .toward...andjover the projecting end ofthepointer. 7

-"Having thus, described the instrument ethic-- ture, I will review its mainsssemblvor disassemlily features. Assume that the instrument is assembled'and mounted ona switchboard as represented 111F151 1. The instrument may be removed from the switchboard withoutopening 'itby taking the nuts from bolts 9 and withdrawing the case from the front 2. The

ing the instrument from the case from the front.

the casing-and left-entire switchboard. 1 v r The complete armature ,assemblymay he plate and the screws :3l which hold plate 38 in minals 42. Align the armature coils with radial "opening 25 and withdraw the armature assembly from the front of the casing. This operation does not disturb "the armature jeweling, lead-in spirals, magnetic damper, or stationary corepointer.45 is in contact or nearly so with arm 39. 7o

' After thus being inserted into place, the coils are structure and thlsfeature is generally applicable to instruments having one, two or more torque elements. Pending return of the armature assembly to the instrument, the front cover may he 2 replaced if desired. I

represented in Fig. 3. This inserting of thea er 75. In accordance with the provisions ofthe patent complete ';"instrument may beremoved" from its casing by removing the front cover and j the three screws ill from the'rear and withdraw-- then be replaced on removed from the casing, leaving the terminals '3 Q- at the rear of the instrument connected, if de- 1 sired, by removing the -front cover and the scale 'drical casing within the reduced rear opening of the cylindristatutes I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof but I desire to have it understood that the apparatus shown is only illustrative and that the invention maybe carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electrical measuring instrument comprising a stationary magnetic core having an outer yoke part and an inner core part secured to the yoke part by a tongue, the inner core part i and the tongue being hook-shaped leaving a radial opening from the center of the inner core part in prolongation with one side of the tongue, a circular flux air gap between the inner core and the outer yoke parts, an energizing coilabo t the tongue for producing flux across said air gap,

an armature'assembly structure comprising a supporting plate removably secure to the front end of said stationary magnetic core, a shaft rotatively supported from said plate in axial,

alignment with the central opening of said inner core part. an armature coil on said shaft with one side adjacent the axis of rotation thereof and of 'suchsize and shape as to thread the inner core part with its outer side rotatable in said circular air gap, a front bearing support for said shaft secured to said plate and a rear bearing support for said shaft comprising a supporting member extending to the rear of said plate through and in alignment with the opening between the tongue and outer yoke Stationary core parts, and with an arm at the rear (if said member extending inward. toward-the axis of rotation in alignment with the radial opening in said inner corepart, whereby when the shaft is rotated to a position where the armature coil is I also in alignment with said radial opening the armature coil as thus assembled for rotation may axis of rotation, each comprising astationary magnetic core made up of one-piece laminations having an outer yoke part and an inner core part connected together by a tongue, the tongue same shaft, a frame removably secured in fixed relation to and at one end of the stationary core assembly, said frame carrying a. bearing for the corresponding end of the shaft, said frame having a supporting member extending toward and beyond the other end of such core assembly in.

alignment with the opening between the tongues and outer yoke parts of the several stationary core structures and an arm on said supporti memberv beyond such other end projecting to the axis of rotation of said shaft in alignment shape as to thread their corresponding inner be inserted in or removed from threading rela tion with said inner core-part without disassembly of said armature assembly structure.

2. An electrical instrument structure comprising a cylindrical casing with openings at front and rear, an'outwardl y projecting plate secured to the cylindrical casing at its front,.

means for securing said plate to a switchboard through which the cylindrical casing extends. 1 said cylindrical casing having a turned-in at its rear reducing the size of such opening, an

-' insulating base member havi g a front circularpart of such dimensions as to fit within the cylinand a reduced rear portion fitting cal casing, means accessible from the rear of the casing for securing said base to the rear of the with the reduced rear part of the base extending through and closing the-rear opening or the cylindrical casing, an electrical instrument secured tothe front or said base within said casing", terminal studs extending through said base for making electrical connection to said instrument from the rear of the casing, and-a cover for said casing removably secured to the front plate, said instrument being removable through the front opening when the cover is re-.

- moved.

'3. an electrical measuring instrument havins :1: of torque elements with a common .with the radial openings in the severa1 inner core members for'rotatively supporting the other end of said shaft, the several armature coils on said shaft having their inner sides lying adjacent the axis of rotation thereof and of such size and core parts with their outer sides rotatable in the corresponding circular air gaps, said armature coils being positioned along said shaft in threading relation with their respective inner core parts when such armature assembly is in place and with said armature coils lying in the same plane so as to be rotated to a position in alignment with r the radial openings in the inner core parts, leadin spirals supported on said frame electrically connected to said armature coils, and an adjustable zero return spring for said shaft supported on said frame, said frame and the parts rotatively and otherwise supported thereby and thereon being axially removable as a unit from said stationary core assembly when the armature coils are rotated in alignment with the radial open-' ings in their corresponding inner core parts.

4. A olyphase alternating "current measurin instrument having a structure as set-forth in claim 3 and provided with stationary magnetic.

screens supported between adjacent torque elements, said screens. having hook-shaped tongue and inner core parts: with radial and air gap openings similar to those orthe stationary core parts and positioned with a corresponding alignment.

I VIRGlL L. WEAVER.

assurances cum-I The following references are of record in the file of this patent: v

ourrnn s'rmrns PATENTS Number Name Date 1,918,023 Fans l July 11, 1983 2,221,643 Lederer u Nov. 12, 1940 2,381,329 Young et al. Aug. 7, 1945 2,389,393 T'homanderzauum; Nov.'30,1 945 Disclaimer 2,419,100.Virgil L. Weaver, Greenwood, Mass. DYNAMOME'IER TYPE ELECTRICAL MEASURING INSTRUMENT.. Patent dated Apr. 15, 1947. Disclaimer filed June 24, 1948, by the assignee, General Electric Company. Hereby enters this disclaimer of claim 2 of said patent.

[Oflicial Gazette August 10, 1948.] 

